Severe ictal hypoxemia following focal, subclinical temporal electrographic scalp seizure activity

Clinical Characteristics and Prognostic Significance of Subclinical Seizures in Focal Epilepsy: A Retrospective Study

INTRODUCTION

The aim was to evaluate the clinical characteristics and prognostic significance of subclinical seizures (SCSs) on scalp video-electroencephalogram (VEEG) monitoring with or without intracranial electroencephalogram (IEEG) monitoring in patients who had epilepsy surgery.

METHODS

We reviewed 286 epileptic patients who underwent subsequent epilepsy surgery during scalp-VEEG evaluation with or without IEEG monitoring between 2013 and 2020, with a minimum follow-up of 1 year. The prevalence and clinical characteristics of SCSs, as well as their prognostic significance, were analyzed.

RESULTS

A total of 286 patients were enrolled for analysis, and 80 patients had IEEG implanted. SCSs were recorded in 9.79% of the patients based on VEEG and 50% based on IEEG. In the VEEG group (n = 286), younger seizure onset (P = 0.004) was associated with the presence of s-SCSs (SCSs detected on scalp VEEG). In the IEEG group (n = 80), temporal lobe epilepsy (P = 0.015) was associated with the presence of i-SCSs (SCSs detected on IEEG). Of 286 patients, 208 (72.73%) were seizure-free in the VEEG group, and 56 0f 80 patients (70%) were seizure-free in the IEEG group through the last follow-up. In the VEEG group, the presence of s-SCSs did not affect seizure outcome; predictors of seizure recurrence were longer epilepsy duration (P = 0.003, OR 1.003, 95% CI 1.001-1.005), history of focal to bilateral tonic-clonic seizure (P = 0.027, OR 1.665, 95% CI 1.060-2.613), nonspecific pathology (P = 0.018, OR 2.184, 95% CI 1.145-4.163), and incomplete resection (P = 0.004, OR 2.705, 95% CI 1.372-5.332). In the IEEG group, i-SCSs were significantly associated with seizure outcome (P = 0.028, OR 0.371, 95% CI 0.153-0.898).

CONCLUSION

The rate of SCSs captured on IEEG monitoring was higher than that on VEEG monitoring during presurgical evaluation. SCSs detected on VEEG monitoring were associated with younger seizure onset. SCSs detected on IEEG monitoring were associated with temporal lobe epilepsy and also predicted surgical outcomes in focal epilepsy.

The role of devices in managing risk

Over the last few years, there has been significant expansion of wearable technologies and devices into the health sector, including for conditions such as epilepsy. Although there is significant potential to benefit patients, there is a paucity of well-conducted scientific research in order to inform patients and healthcare providers of the most appropriate technology. In addition to either directly or indirectly identifying seizure activity, the ideal device should improve quality of life and reduce the risk of sudden unexpected death in epilepsy (SUDEP). Devices typically monitor a number of parameters including electroencephalographic (EEG), cardiac, and respiratory patterns and can detect movement, changes in skin conductance, and muscle activity. Multimodal devices are emerging with improved seizure detection rates and reduced false positive alarms. While convulsive seizures are reliably identified by most unimodal and multimodal devices, seizures associated with no, or minimal, movement are frequently undetected. The vast majority of current devices detect but do not actively intervene. At best, therefore, they indicate the presence of seizure activity in order to accurately ascertain true seizure frequency or facilitate intervention by others, which may, nevertheless, impact the rate of SUDEP. Future devices are likely to both detect and intervene within an autonomous closed-loop system tailored to the individual and by self-learning from the analysis of patient-specific parameters. The formulation of standards for regulatory bodies to validate seizure detection devices is also of paramount importance in order to confidently ascertain the performance of a device; and this will be facilitated by the creation of a large, open database containing multimodal annotated data in order to test device algorithms. This paper is for the Special Issue: Prevent 21: SUDEP Summit - Time to Listen.

Staff Response Times in the Epilepsy Monitoring Unit: A Study of Diurnal/Nocturnal Variability

Although inpatient epilepsy monitoring units (EMUs) are generally safe, seizures in this setting can still produce significant morbidity. The MORTEMUS (MORTality in Epilepsy Monitoring Unit Study) study revealed that the most feared consequence of an unattended seizure-sudden unexpected death in epilepsy (SUDEP)-does occur rarely in the EMU. Nearly all cases identified in that study occurred in the evening. The hypothesis for this study is that unwitnessed seizures would be more likely to occur during the night shift, and that response times to seizures would be slower at night, due to multiple variables. A retrospective video-EEG review of all seizures captured in our EMU during a 4-week period in 15 patients admitted was conducted. The time between seizure onset and the arrival of an attendant at the bedside was measured. There were 16 diurnal and 14 nocturnal seizures identified. The median response time during the day shift was approximately 22 ± 28 (0-80) seconds during the day shift, and 49 ± 93 (0-360) during the night shift (Mann-Whitney U test, P = 0.03). There were six seizures that were subclinical or showed subtle clinical signs (head turning or eyes opening), including one prolonged seizure lasting nearly 18 minutes, which all occurred in the evening, went unattended, and were excluded from the statistical analysis. These preliminary findings indicate a statistically significant delay in nursing response times to seizures in the EMU during the night shift. All unattended seizures occurred in the evening. More research is needed to study human factors, systems issues, or patient-related/physiological factors that slow response times.

Severe Respiratory Acidosis in Status Epilepticus as a Possible Etiology of Sudden Death in Lesch-Nyhan Disease: A Case Report and Review of the Literature

INTRODUCTION

Lesch-Nyhan disease (LND) is an X-linked disorder of purine metabolism, associated with self-mutilation, dystonia, and chorea. Seizures are uncommon in LND. Patients with LND are at risk for sudden and unexpected death. The etiology of this is unknown, but appears to occur from a respiratory process. We propose that respiratory failure secondary to subclinical seizure may lead to sudden death in these patients.

CASE

We report a case of an 11-year-old boy with LND who had two episodes of nocturnal gasping. The second event was immediately followed by a 10 min generalized seizure. Upon arrival at the hospital, an arterial blood gas test revealed a severe respiratory acidosis. Following aggressive treatment of his seizures, this patient did well, and was discharged home on oxcarbazepine with rectal diazepam. No further seizures have been noted in 1 year of follow-up.

CONCLUSIONS

In this case report and review, we hypothesize that sudden death from respiratory failure in Lesch-Nyhan disease may in some cases be due to seizure-induced respiratory failure, akin to sudden unexpected death in epilepsy (SUDEP). We suggest screening for paroxysmal respiratory events; consideration of electroencephalography for patients with LND presenting in respiratory distress or failure; and consideration of more aggressive treatment of seizures in these patients. Brief Summary:We present an 11-year-old boy with Lesch-Nyhan disease (LND) who developed respiratory failure and severe respiratory acidosis from his first known seizure, which evolved to subclinical status epilepticus. We propose that patients with LND have a predisposition to respiratory failure and sudden death, which in some cases may be provoked by seizure (sudden unexpected death in epilepsy, or SUDEP).

From unwitnessed fatality to witnessed rescue: Nonpharmacologic interventions in sudden unexpected death in epilepsy

Sudden unexpected death in epilepsy (SUDEP) risk reduction remains a critical aim in epilepsy care. To date, only aggressive medical and surgical efforts to control seizures have been demonstrated to be of benefit. Incomplete understanding of SUDEP mechanisms limits the development of more specific interventions. Periictal cardiorespiratory dysfunction is implicated in SUDEP; postictal electroencephalography (EEG) suppression, coma, and immobility may also play a role. Nocturnal supervision is protective against SUDEP, presumably by permitting intervention in the case of a life-threatening event. Resuscitative efforts were implemented promptly in near-SUDEP cases but delayed in SUDEP deaths in the Mortality in Epilepsy Monitoring Unit Study (MORTEMUS) study. Nursing interventions--including repositioning, oral suctioning, and oxygen administration--reduce seizure duration, respiratory dysfunction, and EEG suppression in the epilepsy monitoring unit (EMU), but have not been studied in outpatients. Cardiac pacemakers or cardioverter-defibrillator devices may be of benefit in a few select individuals. A role for implantable neurostimulators has not yet been established. Seizure detection devices, including those that monitor generalized tonic-clonic seizure-associated movements or cardiorespiratory parameters, may provide a means to permit timely periictal intervention. However, these and other devices, such as antisuffocation pillows, have not been adequately investigated with respect to SUDEP prevention.

Sudden unexpected death in epilepsy: from the lab to the clinic setting

Sudden unexpected death in epilepsy (SUDEP) is defined as sudden, unexpected, witnessed or unwitnessed, non-traumatic, and non-drowning death in a patient with epilepsy. Sudden unexpected death in epilepsy is probably the most common cause of epilepsy-related deaths. Many predisposing and initiating factors may coexist and contribute to SUDEP, but the mechanisms are poorly understood. Cardiac and respiratory deregulation seems to have a major role in SUDEP. Here, we review several advances in understanding the mechanisms involved in SUDEP.